Subnano-Pd@SiO2 core shell materials were prepared by a one-pot method in a microemulsion made up of cetyltrimethyl ammonium bromide/n-butanol/cyclohexane with newly prepared Pd(NO3)2 solution as raw material. Pd subnanoclusters with an average size of 0.7 nm are uniformly dispersed in the entire SiO2 nanospheres with a high loading amount of 4% on the basis of the mass of SiO2. The physico-chemical properties of the Subnano-Pd@SiO2 were characterized by TEM, XRD, XPS, and N2 adsorption-desorption. The catalytic performances of Subnano-Pd@SiO2 for the hydrogenation reaction of aromatic nitro compounds were investigated. The results showed a 99.5% yield of aniline was achieved through the hydrogenation of nitrobenzene under mild reaction conditions of 50 ℃ and 1.0 MPa H2 for 4 h. Meanwhile, Subnano-Pd@SiO2 was efficient for the hydrogenation of various aromatic nitro compounds to give high yields (98.5%~100%) of arylamines. The activity of Subnano-Pd@SiO2 did not decrease significantly even after being recycled for 4 times.